Design of a multichannel potentiostat and its application to corrosion testing of a nickel-aluminum bronze

Abstract

A setup for potentiostatic testing of eight specimens at different potentials in a common electrolyte pool was developed. The potentiostat requires only one reference electrode and one counter electrode to control all working electrodes and its design is easily scalable with respect to the number of channels. The system was applied to assess the effect of chloride, sulphate, and bicarbonate in fresh water-typical concentration on a nickel-aluminium bronze, assuming some anodic polarization by stainless steel with and without microbially induced ennoblement. Chloride and sulphate activate corrosion, bicarbonate has a passivating effect, and its combination with chloride and sulphate promotes localized corrosion. The susceptibility of nickel aluminium bronze to localized corrosion is high in fresh water when polarized anodically. Potentiostatic corrosion testing may yield practically relevant results for systems with slow kinetics.